Exhaust device for air-motor-operated player-pianos.



M. CLARK.

I EXHAUST DEVICE FOR AIR MOTOR OPERATED PLAYER PIANOS.

v APPLiCATiON FILED DEC-26.1917. 1,298,292. Patented Mar. 25,1919.

2 SHEETS-SHEET 7- M. CLARK.

EXHAUST DEVICE FOR AIR MOTOR OPERATED PLAYER PIANOS.

APPLICATION FILED DEC. 26. I917- 1,298,292. Patented Mar. 25, 1919.

2 SHEETS-SHEET 2.

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UNITED STATES PATENT oFFroE.

MELVILLE CLARK, or crrrcneo, ILLrNoIs, Ass sno t To anrvrnnn oLn tK rrnvo COMPANY, or CHICAGO, rnnrn'ors, A conronATIo v or IILLINQIQ.

EXHAUST DEVICE AlB-MOTOR-OPEBATE D PLAYEIVPIANOS.

Specification of Letters Patent.

Patented Mar, 25, 1919.

Application filed December 26, 191.7. Serial No. 208,764.

To all whom it may concern:

Be it known that I, MELVILLE CLARK, a citizen of the United States,residing at Chicago, in the county of Cook and State of Illinois, haveinvented certain new and useful Improvements in Exhaust Devices forAir-Motor-Operated Player-Pianos, of which the following is aspecification, reference being had to the accompanying drawings, formingapart thereof.

The purpose of this invention is to provide an improved construction ofthe exhaust devices and connections therefrom for the pneumatic actionof an automatic piano player for the air motor which drives thecontrolling note sheet thereof.

It consists in the elements and features of construction shown anddescribed, as indicated in the claims.

' In the drawings Figure 1 is .a fore-and-aft sectional view of theexhaust or vacuum-producing devices in conjunction with a side elevationof an automatic player equipped with this invention.

Fig. 2 is a forward side elevation of said exhaust or vacuum-producingdevices.

Fig. 3 is a section at the line, 8-3, on Fig. 2.

In the drawings the pneumatic actiori df an automatic player isconventionally shown at A, and the motor for operating the note sheetthereof is conventionally shown at B. 1 is the vacuum chamber of thepneumatic action;.2 is the vacuum chamber of the air motor. 3 is theduct board on which are mounted the exhaust devices in the form ofpumpers, t4c, which are at the rear of said duct board, the main hightension exhaust chamber or receiver is on the forward side of said ductboard, the governing bellows, 7, for limiting the exhaust tension whichcan be derived from the main exhaust bellows or receiver, 5, foroperating the air motor, said governor bellows being mounted on the rearside of said duct board; and an auxiliary low-tension bellows orreceiver, 6, of which the base-board, 6 ,-is mounted cross-wise of oneend of the duct board, 3. .8 is a conduit leading from the main exhaustbellows or receiver, 5, to the vacuum chamber, 1, of the pneumaticaction. 9 is a conduit leading from the main exhaust bellows orreceiver, 5, by way of the governor bellows, 6, to the vacuum chamber 2,of the air motor.

As thus far described, except as to the auxiliary low-tension bellows,6, the. construction and operation is familiar in exhaust devices forpneumatic players having an air motor for driving the note sheet. Theoperation of the-pumpers producing partial vacuum in the'high tensionbellows, or recelver, 5, causing said bellows tobe collapsed against thereslstance of its high tension spring, 12, maintains a partial vacuum inthe vacuum'chamber', 1,o f the pneumatics, operating the playingdevicesin a manner requiring no further description here. At the same time, andby the same operation of the pumpers (or any other exhaust devices thatmay be employed) a certain degree of exhaust tension or a partial vacuumis produced in the governor bellows, 7, which is determined by thetension of its exp nding p i g, 13, which yield o permit the bellows tocollapse and seat the valve, 14, at the port of communication of saidgovernor bellows with the main exhaust bellows or receiver, 5, when acertain de gree of exhaust tension .1 partial vacuum is produced, andthus the degree of exhaust tension or partial vacuum operating upon theair motor is governed in a manner well understood, so as not to exceedthat which will thus collapse 1 g vernor bellows and seat its valve asstated.

In the operation of an automatic player provided with exhaust devices ofthe character sc ibed a ha ing n air m r for operating the note sheet,it Wi l obviously occur that if the degree of exhaust tension or partialvacuum maintained bythe pumpers in the main exhaust bellows or receiver,is r th P rpo e fp aying ly, kept for any length of time b low thedegree necessary for collapsing the governor bellows to seat its valve,there will be no actual government'or control effected by said governorbellows upon the air tension operated upon the air motor, but, on thecontrary, the degree of exhaust tension in the main high tension bellows orreceiver, 5, varying from said degree less than suflicient to seat thegovernor bellows valve downward, will operate with similar variationupon the air motor; and it will also beunderstood, asis observed inexperience, that under those circumstances it will-be impossible to,,keep the air moving through the chambers of "the air motor adequatelytomaintain its speed,

because if the operator increases the rate of pumping for the purpose ofthus operating the motor, he will immediately produce a higher tensionin the main exhaust bellows or receiver, than that needed for the purpose of the soft .playing which is being desired. That is to say, it isdifiicult to maintain the uniform or proper speed of the motor, andparticularly to maintain a high speed of the motor for rapid playing,While at the same time playing softly, in a structure equipped in thismanner. The purpose of the present invention is to obviate this defect.Upon considering what happens under the conditions above stated, it willbe seen that the difficulty mentioned arising from the fact that it isimpossible to maintain the movement of an adequate volume of air throughthe air motor and its connections with the exhaust devices by lightpumping, occurs because with the necessary high tension spring forexpanding the high tension bellows or receiver, 5, a very short movementof the moving member of said bellows from its most expanded position,puts the spring under tension in excess of that which is permissible forthe low exhaust tension requisite for the soft playing, and inconsequence the air is drawn out of the vacuum chambers in impulsesfollowing the strokes of the pumper, so that both the playing and themotor movement reflect these strokes by pulsations in the playing;instead of being steady, as it is the purpose of the yielding exhaustchamber or receiver to make them, and which it does make them when itcan be held collapsed to a sufficient extent so that its range ofexpansion shall meet the air requirement of the playing devices and themotor in the intervals from stroke to stroke of the pumpers. And it willbe observed that this lack of a sustained pull is particularlydetrimental to the action of the air motor, because the parts in itwhich are to be moved, and the parts which it is to move in propellingthe note sheet, upon losing their speed cannot be caused to recover itinstantly, and thus it steadily drops back While this conditioncontinues; and it is therefore impossible to maintain a high speed forrapid playing when playing very softly, as is often desired.

This defect is obviated in the structure shown in the drawings by theprovision of the low tension exhaust bellows or air receiver, 6, thatis, one whose expanding spring yields to permit the collapse of thebellows at a lower tension than that which is necessary to collapse thegovernor -bellows 7. Said low tension bellows lever has itscommunication with the exhausting means through the port, 15, controlledby valve, 16, seating inside said low-tension bellows, and openinginward, said valve being mounted upon a rock shaft, 18, which extendsoutside the said lowtension bellows and has on its outer ends a crankarm, 18, which is engaged by a tappet, 19, carried by the moving memberof the main high tension bellows, 5, said tappet being positioned sothat it encounters said crank arm and opens the valve, 16, in the verylast part of the expanding movement of said moving member of the mainbellows, that is, when the exhaust tension operating in said main orhigh tension bellows is approaching the lowest point at which said mainhigh tension bellows is adapted to maintain the tension. lVhen thevalve, 16, is thus opened, the exhausting devices operate immediatelythrough the connection of the pumpers with said low tension bellows, andsaid bellows being collapsed against the resistance of its low tensionspring 6", operates thereafter for producing a continuous pull at lowtension upon the vacuum chambers, both of the pneumatic action and ofthe motor, and so continues the operation both of playing and of drivingthe note sheet,'steadily while the tension is such as to produce a softplaying. The capacity of this low tension bellows may easily be madesuch that the volume of air which is drawn in its expan sion issufficient to give the motor not only a steady speed, but, if desired, ahigh speed, while light or soft playing is produced by the low tension.

I'claim:

1. In an automatic player having a pneumatic player action and an airmotor for 1 actuating the note sheet, in combination with a vacuumchamber of the pneumatic action and the vacuum chamber of the air motor,an exhaust system comprising exhausting means, a high tension exhaustreceiver connected with the exhausting means, and a low tension exhaustreceiver in com munication with the exhausting means; the tensioningmeans of the high and low tension receivers respectively, being relatedat the tensioning capacity'so that the low tension receiver remainscollapsed until the high tension receiver is nearly fully expanded;conduits by which both saidreceivers communicate at the same time bothwith the pneumatic action vacuum chamber and with the air motor vacuumchamber;

a governing bellows interposed in the air conduit between the tworeceivers; a valve which said governing bellows operates for governingthe air tension operating upon the low tension receiver, and a springresisting the collapse of said governing bellows adapted to permit it tocollapse and seat the governing valve upon tension in said bellowshigher than the tensioning means of the low tension receiver.

2. In an automatic player having a pneumatic player action and an airmotor for actuating the note sheet, the combination with a vacuumchamber of the pneumatic action and the vacuum chamber of the air motor,an exhaust system comprising exhausting means, a high tension exhaustreceiver connected With the exhausting means; a 10W tension exhaustreceiver in' communication With the exhausting means, the tensioningmeans of the high and loW tension receivers respectively, being relatedas to tensioning capacity so that the low tension receiver remainscollapsed until the high tension receiver is nearly fully expanded;conduits from said exhaust system to the vacuum chamber of the pneumaticplayer action and to the vacuum chamber of the air motor respectively; avalve which controls the communication of the low tension receiver Withthe exhausting means, and mechanical connections from the moving memberof high tension receiver for opening said valve near the limit of theexpansion of the high tension receiver.

In testimony whereof, I have hereunto set my hand at Chicago, Illinois,this 22nd day of December, 1917.

MELVILLE CLARK.

Copies 01' this patent may be obtained for five cents each, byaddresling the Commissioner 0! Patents, Washington, D. 0."

